Pending U.S. patent application Ser. No. 300,719 entitled "Fuel Distribution Valve" filed Sept. 10, 1981 in the names of Robert M. Halvorsen and Jeffrey B. Hurst and of common assignee herewith describes an improved fuel flow distribution valve for supplying fuel nozzles in a gas turbine engine.
As shown in FIG. 1, the fuel distribution valve of that application includes a valve housing 30 having an inlet 40 that conveys fuel across a spring biased pressure relieved filter assembly 44. The filtered fuel is then conveyed to an elongated spool valve 46 that is in a close tolerance diametrical fit relationship with the wall of a bore through a valve liner 50. Valve 46 includes a plurality of holes 60 which can be brought into registry with holes 58 in the valve liner 50 to allow fuel flow to discharge ports 70 through passages 56, 71.
In the past, the valve housing 30, valve 46 and valve liner 50 have been made of an aluminum alloy, such as Type C355-T6 for the housing and Type 6061-T6 for the valve and valve liner. Prior art workers have expressed some concern that the spool valve holes 60 and valve liner holes 58 might suffer erosion in use as a result of pressurized fuel flow therethrough. To reduce or avoid the erosion possibility it was proposed to make the spool valve and valve liner out of a wear resistant stainless steel such as Type 440C stainless steel. However, a fuel distribution valve constructed in this manner exhibited spool valve binding when the assembly was operated at only 30.degree. F., the binding resulting from the large difference between the thermal expansion coefficient of the aluminum housing (e.g. 13.times.10.sup.-6 in/in/.degree.F.) and that of the stainless steel liner and spool valve (e.g. 8.times.10.sup.-6 in/in/.degree.F.).